MacBook doesn’t connect to internet

A little info and context would help us to help you.

What model/year computer?

How are you trying to connect, hotspot, wifi, ethernet, public access, ... ?

Error messages, what happens when you try to connect?

Are you running any third party anti virus apps or apps that claim to protect, clean, boost performance, etc? If so, uninstall these third party apps. Are you using a proxy or VPN?

If you are using the Safari browser you can try shutting down Safari then while pressing and holding the shift key, launch Safari. This will launch Safari in a clean state.

Uninstall AVAST. It is using system resources while providing no benefit and it may cause issues. If you VPN is not allowing traffic to the problem sites you'll have to uninstall the VPN. Public VPNs provide no security or privacy.

Your MacBook might be on WiFi but with no Internet connection for a range of different reasons. It could be down to your router, your Internet service provider, or your MacBook software. We often use the terms interchangeably, but your WiFi is not actually the same as your Internet connection. Wi-Fi connects you to a local network. And usually, that network connects to the Internet. Your router has an ethernet cable connected to the back of it. If you were to unplug that cable you’d lose Internet connection. But you’d still be able to connect to the Wi-Fi network. If you leave in a rural area, maybe you should change your internet connection to a rural broadband sattelite connection provided by https://usave.co.uk/broadband/rural-broadband/. Good luck!